Interlocked type wire strand

ABSTRACT

A lock type wire strand for aerial tramways and the like has the bottom portions of the interlocked outer wires prolated, or bulged. The prolated portions of the interlocked wires extend into the interstices between wires in the next adjacent layer of wires under the interlocked layer of wires and contacts adjacent wires in said next adjacent layer to provide additional resistance against compression forces and relieve secondary bending strains in the interlocked wires of the strand.

United States Patent Hiller et al. [451 Sept. 19, 1972 [54] INTERLOCKEDTYPE WIRE STRAND 2,106,060 l/l938 Ostrander "57/145 X [72 Invemo C D2,385,24l 9/l945 White.. ..57/l45 1 rs :1 w 22 i" 3,188,791 6/1965,Grimes et al ..57/l6l x both of 3,425,207 2/1969 Campbell ..57/ I45 [73]Assignee: Bethlehem Steel Corporation Primary Examiner-Donald E. Watkins[22] April 23, 1971 Attorney-Joseph J. O Keefe [2]] Appl. No.: 136,687[57] ABSTRACT I r p A lock type wire strand for aerial tramways and the[52] us. Cl. ..57/145 like has the bottom p i of the interlocked oute s1rm. Cl. ..D07b 1/06, D07b 1/08 wires prelated. or s The PrelaredPortions of the [58] Field of Sear h 57/144, 145 4 1 1 1 3 interlockedwires extend into the interstices between 57 9, 15 39 wires in the nextadjacent layer of wires under the interlocked layer of wires andcontacts adjacent wires in 5 References Cited said next adjacent layerto provide additional resistance against compression forces and relievesecon- UNITED STATES PATENTS dary bending strains in the interlockedwires of the 338,9l3 Batchelor ..57/l46 Smmd' f 1,818,845 Fess] ..57/l6lX 12 Claims, 7 Drawing Figures Murmur 19 m2 INVENTORS Carl Duane///'//er Hora/0 144 Aorye BY ATTORNEY INTERLOCKED TYPE WIRE STRANDBACKGROUND OF THE INVENTION The present invention relates to lock typewire strands and more particularly to lock type strands which areparticularly resistant to fatigue failures due to transverse loadings.

lnterlocked outer wires are frequently used on wire strands which are tobe subjected to transverse compressional forces such as may result fromthe passage of tramway wheels or the like over the strand. Theinterlocked sections give the strand a smoother outer surface andextended wear resistance and also provides additional bearingstrength'over that which is available with the use of round wires. Thetwo most common types of interlocked strand are so-called half-lock, orO-H lock, and full-lock, or Z-lock strand. Full, or Z- lock, strandconsists or one or more outer layers of interlocked Z-shaped wires.Half-locked strand is comprised of alternating H, or rail, shaped wiresand substantially round wires. The round wires are interposed betweenthe extensions on the H, or rail shaped wires.

Customarily, the interlocked wires of a fully locked strand aresuperimposed or supported upon a subjacent layer of half locked wires toprovide a more even supporting surface for the Z-shaped wires. Thehalf-lock layer of wires is then supported in turn upon a layer ofconventional round wires. An example of this preferred construction isshown in US. Pat. No. 2,385,241 to White. Frequently, however, thefull-lock layer of wires may be superimposed directly over a layer ofround wires. As shown in the White patent, there may also be severalsuperimposed layers of full-lock or half-lock wires or both in onestrand. In any of these constructions, however, an interlocked layer ofwires of some nature is finally superimposed upon a layer of roundwires. When a transverse compressional load is applied to the strand,such as may occur when a tramway wheel passes over the strand, themomentarily high compression loading may cause such high secondarystresses and strains in the outer portions of the strand as to causebreakage of the interlocked wires even though their tensile strength isnot exceeded, or even approached. This problem of breakage has beenfound to be particularly troublesome in a layer of interlocked wireswhich directly overlies a subjacent layer of round wires, and isparticularly acute when the layer of interlocked wires overlying a layerof round wires happens to be a layer at or near the surface of thestrand.

Since a layer of interlocked wires directly supported upon a layer ofround wires is usually a half-locked layer, the problem of breakage moreoften occurs in half-lockedstrand. Full-locked strand, however, can alsofrequently suffer such wire breakage. The reasons for these breakagesappears to be that the heavy transverse compressional loads placed uponthe strand by tram car wheel loadings and the like subject the outerwires of the strand to secondary bending stresses which are above thefatigue endurance limit of the individual wires. Many tramway tracksstrands consequently develop numerous wire breakages at a very earlydate relative to the actual wear of the strand and its normally expectedlife. Such premature breakages of the wires may cause sudden anddisastrous failure of the entire strand if the wire breakages are notpromptly detected. It is frequently difficult to detect breakage of anindividual interlocked wire, however, because the wire will be locked inthe strand rather than protruding from the strand as will usually occurin a normal rope or strand in which broken outer wires occur, and it isuneconomic in any event to have to replace an entire strand when onlythe outer wires are damaged.

SUMMARY OF THE INVENTION The foregoing difficulties of prior lock-wirestrands subject to transverse loading have been successfully obviatedaccording to the present invention by stranding the interlocked layer ofwires and the immediately subjacent layer of round wires in thelock-strand with the same lay length and direction and providing aprolated profile to the bottom of at least some of the interlockedwires. The prolated sections of the interlocked wires are oriented sothey extend into the interstices between adjacent wires of the subjacentlayer to provide support against transverse loading of the interlockedwires.

The arrangement of the invention substantially eliminates prematurebreakage of the interlocked wires of the strand due to transverseloading of the strand since the prolated lock wires are. supported notonly by the contiguous lock wires on either side but are also providedwith contiguous support by the underlying layer of wires. Secondarybending stresses are thus so far eliminated that what little bendingstress remains does not begin to approach the fatigue endurance limitsof the individual lock wires of the strand. Premature breakage of theouter wires of the stand is thus largely eliminated.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a portion of a half-lockwire strand according to the invention partially cut away to reveal thelay of the wires.

FIG. 2 is a cross section of FIG. 1 at 2-2.

FIG. 3 is an enlargement of a portion of FIG. 2 to better show theprolate profile of the interlocked wires.

FIG. 4 is a portion of a full-lock wire strand according to theinvention partially cut away to reveal the lay of the wires.

FIG. 5 is a cross section of FIG. 4 at 5-5.

FIG. 6 is an enlargement of a section of FIG. 5 to better show theprolate profile of the interlocked wires.

FIG. 7 is a cross section of a wire strand according to the invention inwhich a full-lock layer of wires is supported-upon a half-lock layer ofwires having the prolate profile of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIGS. 1, 2 and 3 there isshown a half-lock wire strand 11 comprised of a center wire 13, fourwires 15 laid about the center wire 13 in a right hand layer, oroperation, l6, 10 wires 17 laid about the wires 15 in a left handoperation 18 and an outer layer 19 of 20 wires laid in a left handoperation about the wires 17 with the same angle of lay as the wires 17.There are two types of wires in the layer 19 which comprises a so-calledhalf-lock or 0-H type interlocked layer. Layer 19 is comprised of roundwires 21 alternating with H, or rail, shaped wires 23 which extendpartially about the circumference of the round wires 21 so that theentire layer of wires is gripped or locked together into a unitarylayer. The bottom of each rail section 23 is prolated as shown at 25 sothat it extends down partially into an interstice between two adjacentwires 17 of the subjacent layer of wires 18 and is partially supportedagainst two contiguous wires 17 of the layer of wires 18. Thealternating round wires 21 on each side of the rail sections 23 aremeanwhile supported directly upon the underlying wires 17. The railsections 23, therefore, which constitute, because of their shape, amajor proportion of the surface contact area of the strand, aresupported against transverse compression forces by their gripping actionon adjacent round wires 21 of the interlocked layer 19 and also bydirect contact through their prolate bottom sections with two contiguouswires 17 of the subjacent layer of wires 18. EAch rail section 23,therefore, because it is nested within a pocket between four adjacentwires is so supported that it suffers substantially no secondary bendingstress when subjected .to transverse compression forces and the fatiguelimit of the rail sections 23 is thus not exceeded before the remainderof the strand is subjected to substantial wear. 1

While the support of the rail sections 23 is particularly'important whenthe layer of half-lock wires is the surface layer of the strand, it willbe understood that the half-lock layer might itself constitute anunderlying operation or layer of the strand.

in FIGS. 4, and 6 there is shown a full-lock, or Z- lock, strand 31having a central wire 33 surrounded by a layer 34 comprised of six roundwires 35 having a right hand'lay, a layer, or operation, 36 of 12 wires37 laid about the wires 35 with a left hand lay, and 24 Z- profile wires39 laid about the wires 37 with a left hand lay and the same lay angleas the wires 37 to form a fully locked layer of wires 41. The bottomsection of every other Z-profile wire 39 is bulged, extended or prolatedas shown at 43 so that it extends into the interstice between twoadjacent wires 37 of the subjacent layer, or operation, of wires 36 andis supported by two contiguous. wires 37 in this layer. If desired theZ- profile wires 39a between the prolated wires 39 may have a slightdepression 45 formed as shown on their undersides which seats partiallyover the immediately underlying wire in the subjacent layer of wires 37.

It will be seen that due to the prolated bottom portionof every other'Z-profile wire 39, that each wire 39 and 39a of the full locked sectionor layer 41 is thoroughly supported against transverse compressionalforces.

It may be desirable in some cases rather than using a prolated Z-profilewire as explained supra, to use a preferred prolated half-lock layerunder the outside full-locked layer of wires as illustrated in crosssection in FIG. 7. As shown in FIG. 7, a regular Z-profile layer 50 ofwires 51 is directly supported upon the relatively even surface of asubjacent layer 52 of half-locked wires 53 and 55. The bottoms of therail section wires 55 of layer 52 are prolated according to the presentinvention for complete support against any transverse compression forcessuch as may arise from tramway car loadings or the like. Since thehalf-lock layer, or operation, 52 of wires 53 and 55 is completelysupported against transverse loads, it will be seen that thesuperimposed layer or operation 50 of full-lock wires 51 is alsocompletely supported against transverse compression loads. I

In the construction shown in FIG. 7 every wire 51 overlying aprolated'wire 55 in the half-lock operation of wires 52will have aconventional flat bottom profile, while every other wire 52a overlying around wire in a half-lock layer 52 will preferably, as shown, have aslightly concave bottom profile to provide additional bearing surfacearea between the Z-profile wire 51a and the subjacent round wire 53. Inthis case, of course, the two operations of interlocked wires 51 and 52will have the same direction and angle, or length, of lay. If

I the two operations of interlocked wires are not, as may portions ofthe prolated wires 55 of the subjacent-halflock layer 52.

While the prolated sections of the various interlocked wires accordingto the invention are shown as rounded extensions on the normallyflattened under portions of the interlocked wires, the prolated sectionsmay actually take different shapes so longas they are extended betweenand into contact with adjacent wires of a subjacent layer of supportingwires. The profile of the prolated sections might, for instance, beangular or even depressed on the portions which contact the adjacentwires. It will ordinarily be found more convenient, however, to make theprofile substantially evenly rounded as shown as this contour is moreeasily attained in a conventional wire drawing operation such as isusually used to shape the constituent interlock wires. A fairly evenlyrounded profile may also be beneficial in an interlocked strand which isto be subjected to bending or the like.

It will also be recognized that the conventionally round wires of thesubjacent supporting layers may have more or less conventional crosssections other than round such as oval, ovoid such as, for example, eggshaped or the like, or may even almost approach a rectangular shape. Theshape of the underlying wires is not significant so far as the inventionis concerned so long as there are interstices between the underlyingwires for the prolated portions of the overlying wires to extend into asecure support for the superimposed interlocked wires.

We claim:

1. A wire strand comprising:

a. a first interlocked layer of wires having prolated lower profiles onat least some of the constituent wires,

b. a second subjacent layer of wires immediately under said interlockedlayer of wires having the same lay angle and direction of lay as saidinterlocked layer of wires,

0. the prolated sections of said first layer of wires extending into theinterstices between wires of said second subjacent layer and being insubstantial contact with adjacent wires of said second layer.

2. A wire strand according to claim 1 wherein said wires of said secondlayer have cross-sectional profiles selected from the group consistingof substantially round, oval and ovoid profiles.

3. A wire strand according to claim 1 wherein said first interlockedlayer of wires is comprised of halflocked wires.

4. A wire strand according to claim 3 wherein each rail section of saidhalf-locked wires has a prolated bottom portion.

5. A wire strand according to claim 4 wherein said half-locked layer ofwires is the outermost layer of wires in said strand.

6. A wire strand according to claim 4 wherein said half-locked layer ofwires is overlain by a full-lock layer of wires.

7. A wire strand according to claim 6 wherein said half-locked layer ofwires and fully locked layer of wires have same direction and angle oflay and the bottoms of the alternate wires of said fully locked layeroverlying subjacent round wires of said half-locked layer of wires haveslightly concave profiles providing v substantially greater than linecontact between the said fully locked wires and the said round wires ofsaid halflocked layer of wires.

8. A wire strand according to claim 7 wherein said fully locked layer ofwires is the outermost layer of wires in said strand.

9. A wire strand according to claim 1 wherein said first interlockedlayer of wires is comprised of fully locked wires.

10. A wire strand according to claim 9 wherein at least every alternatewire of said first fully locked layer of wires has a prolated lowerprofile.

l l. A wire strand according to claim 10 wherein said first fully lockedlayer of wires is the outermost layer of wires in said strand.

12. A wire strand according to claim 11 wherein the fully locked wireswhich are not prolated have depressed lower portions contactingunderlying wires.

I! III i i

1. A wire strand comprising: a. a first interlocked layer of wireshaving prolated lower profiles on at least some of the constituentwires, b. a second subjacent layer of wires immediately under saidinterlocked layer of wires having the same lay angle and direction oflay as said interlocked layer of wires, c. the prolated sections of saidfirst layer of wires extending into the interstices between wires ofsaid second subjacent layer and being in substantial contact withadjacent wires of said second layer.
 2. A wire strand according to claim1 wherein said wires of said second layer have cross-sectional profilesselected from the group consisting of substantially round, oval andovoid profiles.
 3. A wire strand according to claim 1 wherein said firstinterlocked layer of wires is comprised of half-locked wires.
 4. A wirestrand according to claim 3 wherein each rail section of saidhalf-locked wires has a prolated bottom portion.
 5. A wire strandaccording to claim 4 wherein said half-locked layer of wires is theoutermost layer of wires in said strand.
 6. A wire strand according toclaim 4 wherein said half-locked layer of wires is overlain by afull-lock layer of wires.
 7. A wire strand according to claim 6 whereinsaid half-locked layer of wires and fully locked layer of wires havesame direction and angle of lay and the bottoms of the alternate wiresof said fully locked layer overlying subjacent round wires of saidhalf-locked layer of wires have slightly concave profiles providingsubstantially greater than line contact between the said fully lockedwires and the said round wires of said half-locked layer of wires.
 8. Awire strand according to claim 7 wherein said fully locked layer ofwires is the outermost layer of wires in said strand.
 9. A wire strandaccording to claim 1 wherein said first interlocked layer of wires iscomprised of fully locked wires.
 10. A wire strand according to claim 9wherein at least every alternate wire of said first fully locked layerof wires has a prolated lower profile.
 11. A wire strand according toclaim 10 wherein said first fully locked layer of wires is the outermostlayer of wires in said strand.
 12. A wire strand according to claim 11wherein the fully locked wIres which are not prolated have depressedlower portions contacting underlying wires.